Field
The present disclosure relates to a display device in which touch sensors are embedded in a pixel array.
Discussion of the Related Art
User interfaces (UIs) are configured to allow users to communicate with various electronic devices, and thus to easily and comfortably control the electronic devices as they desire. Examples of UIs include a keypad, a keyboard, a mouse, an on-screen display (OSD), and a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technology has continuously expanded to increase user's sensibility and handling convenience. UIs have been recently developed to include touch UIs, voice recognition UIs, 3D UIs, and the like.
The touch UI has been essentially adopted in portable information devices, such as smart phones, and use of the touch UI has been expanded to include notebook computers, computer monitors, and home appliances. A technology (hereinafter referred to as “in-cell touch sensor technology”) has been recently proposed to embed touch sensors in a pixel array of a display panel. In in-cell touch sensor technology, touch sensors may be installed in a display panel without an increase in a thickness of the display panel. The touch sensors are connected to pixels through parasitic capacitances. In order to reduce a mutual influence and crosstalk attributable to coupling between the pixels and the touch sensors, one frame period may be time-divided into a period (hereinafter referred to as “display driving period”) in which the pixels are driven, and a period (hereinafter referred to as a “touch sensor driving period”) in which the touch sensors are driven.
In in-cell touch sensor technology, electrodes connected to the pixels of the display panel are used as electrodes of the touch sensors. For example, a common electrode supplying a common voltage to pixels of a liquid crystal display is segmented, and segmented common electrode patterns are used as electrodes of the touch sensors.
A parasitic capacitance connected to the in-cell touch sensors increases due to coupling between the in-cell touch sensors and the pixels. When the parasitic capacitance increases, the possibility of crosstalk increases and touch sensitivity and accuracy of touch recognition are deteriorated. When an alternating current (AC) signal having the same phase as a touch driving signal is supplied to gate lines of the display panel during a touch sensor driving period, the parasitic capacitance of the touch sensor may decrease. This method supplies a gate pulse synchronized with a data voltage of an input image to the gate lines during the display driving period and supplies the AC signal to the gate lines during the touch sensor driving period.
To this end, a power generator produces the AC signal during the touch sensor driving period and supplies the AC signal to a low potential input terminal of a gate driver, and the gate driver supplies the AC signal supplied to the low potential input terminal to an output node through a low potential signal line. However, because the low potential signal line inside the gate driver is coupled with a plurality of thin film transistors (TFTs) through the parasitic capacitance, a waveform of the AC signal supplied to the output node is distorted by an influence of an RC delay. Hence, the AC signal applied to the gate lines of the display panel and the touch driving signal are out of phase with each other. As a result, the related art has the disadvantage of a limit in a reduction in the parasitic capacitance between the touch sensor and the gate line during the touch sensor driving period.